Friends In !14410, specifically on Fedora, I get this build failure https://gitlab.haskell.org/ghc/ghc/-/jobs/2225860. Some kind of crash in some invocation of Haddock to make the docs for ghc-internal. Question: how can I reproduce this failure on my own machine? It builds fine for me. Thanks Simon Error when running Shake build system: at want, called at src/Main.hs:127:44 in main:Main * Depends on: binary-dist at need, called at src/Rules/BinaryDist.hs:311:13 in main:Rules.BinaryDist * Depends on: binary-dist-dir at need, called at src/Rules/BinaryDist.hs:168:9 in main:Rules.BinaryDist * Depends on: docs at need, called at src/Rules/Documentation.hs:137:9 in main:Rules.Documentation * Depends on: _build/doc/html/index.html at need, called at src/Rules/Documentation.hs:214:9 in main:Rules.Documentation * Depends on: _build/doc/html/libraries/index.html at need, called at src/Rules/Documentation.hs:251:9 in main:Rules.Documentation * Depends on: _build/doc/html/libraries/ghc-internal-9.1400.0-9f99/ghc-internal.haddock at cmd, called at src/Builder.hs:404:5 in main:Builder * Raised the exception: Development.Shake.cmd, system command failed Command line: _build/stage1/bin/haddock --verbosity=0 -B_build/stage1/lib --lib=_build/stage1/lib --odir=_build/doc/html/libraries/ghc-internal-9.1400.0-9f99 --dump-interface=_build/doc/html/libraries/ghc-internal-9.1400.0-9f99/ghc-internal.haddock --html '--title=ghc-internal-9.1400.0: Basic libraries' --prologue=_build/doc/html/libraries/ghc-internal-9.1400.0-9f99/haddock-prologue.txt --optghc=-D__HADDOCK_VERSION__=2300 --hide=GHC.Internal.Data.Typeable.Internal --hide=GHC.Internal.IO.Handle.Lock.Common --hide=GHC.Internal.IO.Handle.Lock.Flock --hide=GHC.Internal.IO.Handle.Lock.LinuxOFD --hide=GHC.Internal.IO.Handle.Lock.NoOp --hide=GHC.Internal.IO.Handle.Lock.Windows --hide=GHC.Internal.StaticPtr.Internal --hide=GHC.Internal.Event.Arr --hide=GHC.Internal.Event.Array --hide=GHC.Internal.Event.Internal --hide=GHC.Internal.Event.Internal.Types --hide=GHC.Internal.Event.IntTable --hide=GHC.Internal.Event.IntVar --hide=GHC.Internal.Event.PSQ --hide=GHC.Internal.Event.Unique --hide=GHC.Internal.Unicode.Bits --hide=GHC.Internal.Unicode.Char.DerivedCoreProperties --hide=GHC.Internal.Unicode.Char.UnicodeData.GeneralCategory --hide=GHC.Internal.Unicode.Char.UnicodeData.SimpleLowerCaseMapping --hide=GHC.Internal.Unicode.Char.UnicodeData.SimpleTitleCaseMapping --hide=GHC.Internal.Unicode.Char.UnicodeData.SimpleUpperCaseMapping --hide=GHC.Internal.Unicode.Version --hide=GHC.Internal.System.Environment.ExecutablePath --hide=GHC.Internal.Bignum.Backend.GMP --hide=GHC.Internal.Event.Control --hide=GHC.Internal.Event.EPoll --hide=GHC.Internal.Event.KQueue --hide=GHC.Internal.Event.Manager --hide=GHC.Internal.Event.Poll --hide=GHC.Internal.Event.Thread --hide=GHC.Internal.Event.TimerManager --optghc=-hisuf --optghc=dyn_hi --optghc=-osuf --optghc=dyn_o --optghc=-hcsuf --optghc=dyn_hc --optghc=-fPIC --optghc=-dynamic --optghc=-hide-all-packages --optghc=-no-user-package-db '--optghc=-package-env -' '--optghc=-this-unit-id ghc-internal-9.1400.0-9f99' '--optghc=-this-package-name ghc-internal' '--optghc=-package-id rts-1.0.3' --optghc=-i --optghc=-i/builds/ghc/ghc/_build/stage1/libraries/ghc-internal/build --optghc=-i/builds/ghc/ghc/_build/stage1/libraries/ghc-internal/build/autogen --optghc=-i/builds/ghc/ghc/libraries/ghc-internal/src --optghc=-Irts/include --optghc=-I_build/stage1/libraries/ghc-internal/build --optghc=-I_build/stage1/libraries/ghc-internal/build/include --optghc=-Ilibraries/ghc-internal/include --optghc=-I/builds/ghc/ghc/rts/include --optghc=-I/builds/ghc/ghc/_build/stage1/rts/build/include --optghc=-optP-include --optghc=-optP_build/stage1/libraries/ghc-internal/build/autogen/cabal_macros.h --optghc=-optP-DBIGNUM_GMP --optghc=-outputdir --optghc=_build/stage1/libraries/ghc-internal/build --optghc=-this-unit-id --optghc=ghc-internal --optghc=-Wcompat --optghc=-Wnoncanonical-monad-instances --optghc=-XHaskell2010 --optghc=-XNoImplicitPrelude --optghc=-no-global-package-db --optghc=-package-db=/builds/ghc/ghc/_build/stage1/inplace/package.conf.d --optghc=-ghcversion-file=rts/include/ghcversion.h --optghc=-ghcversion-file=rts/include/ghcversion.h --optghc=-this-unit-id --optghc=ghc-internal --optghc=-Wcompat --optghc=-Wnoncanonical-monad-instances --optghc=-XHaskell2010 --optghc=-XNoImplicitPrelude --optghc=-no-global-package-db --optghc=-package-db=/builds/ghc/ghc/_build/stage1/inplace/package.conf.d --optghc=-ghcversion-file=rts/include/ghcversion.h --optghc=-ghcversion-file=rts/include/ghcversion.h --optghc=-Wno-deprecated-flags --optghc=-Wno-trustworthy-safe +RTS -t_build/stage1/haddock-timing-files/ghc-internal.t --machine-readable -RTS --hyperlinked-source --hoogle --quickjump @/tmp/extra-file-54706448418404-4067-11690 Exit code: 1 Stderr: <no location info>: error: panic! (the 'impossible' happened) GHC version 9.14.0.20250710: idDetails a_alNe Call stack: CallStack (from HasCallStack): pprPanic, called at compiler/GHC/Types/Var.hs:1079:43 in ghc-9.14.0.20250710-7d78:GHC.Types.Var